Ahmad, D., et al. “Development of a Tractor-Pulled Motion Resistance Test Rig for Traction Studies on Towed Narrow Wheels”. International Journal of Agricultural and Biological Engineering, vol. 4, no. 4, Jan. 2012, pp. 21-27, https://ijabe.migration.pkpps03.publicknowledgeproject.org/index.php/ijabe/article/view/541.